I do not know of a specific modeled effect, per se, I have an engineering background and have been performing quantitative analysis of NH temperature data and comparing it with historical sulfate emissions (both natural and anthropogenic). This will be a published work but probably not anything more than a paper in a conference proceeding.

If one performs a strict data analysis, without fudging the data by allocating a higher reflective index to 1960's aerosols than today's, and then takes into account the relative isolation that the arctic experiences from aerosols then a stronger, and longer negative forcing signal from sulfates is seen. Currently it is looking more and more like the long term signal is actually the aerosol driver on PDO variability. (as is currently being theorized about AMO) If this is found to be causative, then it is the long-range cooling effect that is seen in the data. Otherwise it is a long-term effect, not necessarily cloud based, and may otherwise be related to geoengineering. I believe that the GLORY satellite failure, after spending 120 million dollars reworking the delivery mechanism, should never have happened.

Okay. So you said it's 'laughable' that I credit Lindzen's ideas within the realms of possibility. On the other hand Lindzen has solved a number of fundamental problems in climate science in his long career, is one of the most decorated and recognised of living climate scientists (I mean his prizes, awards, honours), he's published around 300 peer reviewed papers, he continues to publish research that is cited by the IPCC, is the author of a standard graduate textbook on atmospheric dynamics, and so on. Maybe you don't know this, because Green groups have told a lot of lies about him.

Meanwhile you are asking me to essentially take your word for it that your own unpublished theory is correct. Don't get me wrong - I congratulate for you developing the theory yourself and wish you the best for your plans to publish. But I ask why do you expect others to take the theory seriously before it has passed a peer review? Indeed, it's not even available to public scrutiny. If you published it on a blog, at least others could criticise it.

You have written,

If one performs a strict data analysis, without fudging the data by
allocating a higher reflective index to 1960's aerosols than today's,
and then takes into account the relative isolation that the arctic
experiences from aerosols then a stronger, and longer negative forcing
signal from sulfates is seen. Currently it is looking more and more
like the long term signal is actually the aerosol driver on PDO
variability. (as is currently being theorized about AMO) If this is
found to be causative, then it is the long-range cooling effect that is
seen in the data. Otherwise it is a long-term effect, not necessarily
cloud based, and may otherwise be related to geoengineering.

So why can't you plot us some graphs showing the correlation you've observed with some explanation of what you're doing?

Meanwhile, as far as I can see, even the orthodox IPCC explanation that sulfate aerosols caused the cooling in the 60s and 70s is in trouble - it's not just Kaufmann's explanation of the 21st century hiatus that is rejected.

- that included as co-authors Mike Wallace and Phil Jones - so another group of very senior and widely-cited climate scientists who also reject the sulfate aerosol explanation of 60s and 70s cooling. I know that Mike Wallace has authored a number of papers on this and his view hasn't changed - he doesn't favour sulfate aerosol cooling for the 60s and 70s cooling.

Meanwhile, another thread emerged in the literature after Steve Schwartz noted that climate models with large climate sensitivity are compenstated with small aerosol forcing and vice versa to reproduce the 20th century temperature anomaly. This thread has been picked up by Jeffrey Kiehl, Reto Knutti and Peter Huybers.

In Knutti's words,

"the most likely and obvious (although not the only) interpretation from the results just above is that the total aerosol effect is smaller than suggested by most aerosol models."

This theory continues to be discussed quite widely in the literature. It's got 109 citations in Google Scholar.

I'll have even more to say about this below.

By the way, you claim that the IPCC AR5 WG1 authors are biased. But listen to this (this is relevant to Knutti's paper - especially when you consider that Knutti is simultaneously one of the WG1 authors on this chapter!) -

There continues to be very high confidence that models simulate realistically the surface temperature on continental and larger scales (Section 9.4.1.1, Figure 9.2). There is likewise very high confidence that models simulate realistically the global-scale surface temperature increase over the historical period, especially the last fifty years (Section 9.4.1.3.1, Figure 9.8). Together with the fact that climate models are based on fundamental physical and biogeochemical principles, these assessments lead to the very high confidence that models generally respond correctly to external forcing like changing greenhouse gases (Box 9.1, Chapter 10–12, 14).
...There is high confidence that many models simulate realistically the observed trend in ocean heat content, although some models show substantial deviations from the observations (Section 9.4.2.2, Figure 9.17). This gives confidence in using climate models to assess the global energy budget (e.g., Box 13.2).

And then try to square this 'high confidence' that the models respond 'correctly' to the radiative forcing with -

The CMIP5 model spread in equilibrium climate sensitivity ranges from 2.1 to 4.7°C and is very similar to the assessment in AR4. No correlation is found between biases in global-mean surface temperature and equilibrium climate sensitivity, which enhances confidence in model simulations of a warming climate even in the presence of errors in the time-mean (Section 9.7.2.1, Figure 9.43).

To me, this is utterly absurd. In so far as the real climate sensitivity of the real earth system is a single number I, personally, have supreme confidence that most of the models in the CMIP5 ensemble are not responding correctly to the radiative forcing but are simulating the temperature anomaly as a result of fudging!

So perhaps we can agree that the AR5 authors are in general biased towards defending climate models despite overwhelming evidence that the models are not doing so well?

> 2) You have variously attempted to quantify the radiative impact of the
> net aerosol effect with some rather wild values in W m-2. In the other
> thread you had no problem with a value as large as 10 W m-2. I'd like to
> confirm that we agree that the fact that the earth is not cooling puts a
> limit on how strong this forcing can actually be.

sure, some limits are there, the problem is that the net warming effects, balanced with the net cooling effects are constrained within significant energy balance assumptions and measurement errors.

If you take the rate of warming from the 1980's and compare it to earlier warming phases you will see that the rather miniscule decrease in SO2 emissions caused a massive shift in the warming trend. And that a relatively minor shift in the late 90's produced another major shift.

Again, it would be great to actually see this correlation plotted in a figure, rather than you asking me to take your word for it. I note that your wording actually suggests the correlation isn't much good - "you will see that the rather miniscule decrease in SO2 emissions caused a massive shift in the warming trend". Wouldn't that suggest it's quite likely this correlation != causation? That the rather miniscule SO2 decrease probably has nothing to do with the great climate shift of the 1976-1995?

> The radiative forcing from the WMGHGs is well constrained at around 1.8 W
> m-2 for CO2, 1 W m-2 from CH4, N20 & CFCs and 0.4 W m-2 for ozone, and 0.1
> W m-2 from stratospheric water vapour, meaning around 3.3 W m-2 since 1750
> (AR5 SOD Fig. 8.17). It is therefore rather absurd to claim that the net
> aerosol effect is greater than around 3.3 W m-2, as a net positive RF is
> required to explain the fact that the earth has warmed, and hasn't cooled.
>
> The same reasoning applies when we narrow in on shorter timeframes. E.g.
> see Fig. 8.19 for the forcing from 1980 and 2011. Do we agree?

I would like to agree. There is some indication that previous tweaks to models to justify the temperature curve (if those tweaks were not accurate) would lead to a much higher "locked in" warming for 395 ppmv CO2 than is currently expected. Which is already pretty devastating.

I think we agree that the net aerosol cooling can't possibly be larger than the positive WMGHG forcing.

> 3) I have shown you the reasoning from Kevin Trenberth, and shown you the
> figures from the relevant papers that show that the top-of-the-atmosphere
> radiative imbalance over the recent warming hiatus period is accurately
> measured, and there is no aerosol fingerprint in the measurements. In the
> opinion of Trenberth, and others, the Kaufmann et al. 2011 PNAS sulfate
> aerosol hypothesis is dismissed out of hand. Are we in agreement that
> there is very little support among experts for aerosols as the explanation
> of the recent warming hiatus? That's not to say it's wrong - but to
> concede that few actually agree with this theory. Okay?

Trenberth is not an aerosols guy. your characterization of Kaufmann is only based on a thread comment by trenberth who says he "doubts it". Stop with the fanciful characterization of a body of work by attributing one person's perspective as indicative of the body of knowledge, The fact is there are more and more studies being presented each month that continue to indicate a significant aerosol cooling effect during the 1998-2012 period. In fact, even the AR5 that you quote so often says,

"While there is high confidence level for a substantial enhancement in the negative aerosol forcing in the period 1950–1980, there is much more uncertainty in the global mean aerosol forcing over the last two decades (1990–2010). Over the last two decades there has been a strong geographic shift in aerosol and aerosol precursors emissions, and there are some uncertainties in these emissions (Granier et al., 2011). In addition to the regional changes in the aerosol forcing there is also likely a competition between various aerosol effects. Emission data indicate a small increase in the BC emissions (Granier et al., 2011) but model studies also indicate a weak enhancement of other aerosol types. Therefore, the net aerosol forcing depends on the balance between absorbing and scattering aerosols for the aerosol-radiation interaction as well as balance between the changes in the aerosol-radiation interaction and aerosol-cloud interactions."

please note that I have already addressed this point strenuously in our dialogue.

page 8-41 lines 8-16

You are correct that Trenberth isn't an aerosol guy. But he is an expert in the earth's energy balance and the greenhouse effect. And Trenberth doesn't need to be an aerosols expert to know that the aerosol hypothesis contradicts the observations of the earth's energy balance.

Meanwhile Kaufmann is not an aerosol guy either. In fact, Kaufmann doesn't appear to be anyone of particular note in the climate science community. Some of his publications are on policy and economics.

Trenberth didn't say he merely "doubts" the aerosol hypothesis. His exact wording was he "doesn't believe it for a moment".

Let me explain this some more. The observations of the energy balance over the period 2001 to the present show that there was a positive radiative imbalance at the top of atmosphere (TOA). This combines accurate satellite measurements of the change in imbalance over time at the TOA - accurate enough to observe the small forcing from the 11-year sunspot cycle - with well sampled and accurate measurements of the ocean heat content.

There is virtually no dispute that the hiatus in warming in the 21st century has proceeded despite a positive radiative imbalance at the TOA. This fact essentially disproves the aerosol hypothesis in one stroke. That is why Trenberth dismisses the theory out of hand.

If the aerosol hypothesis was correct, then reflective aerosols should have reflected additional incoming sunlight in the global average, which would have led to the climate system being essentially in radiative equilibrium for the 2001-present period.

This is not observed!

The physics of all this is very basic, and it seems to me you just don't want to accept these basic facts.

Meanwhile, it is not just Trenberth. It's the whole of NCAR, including Gerry Meehl and John Fasullo and Jeffrey Kiehl. As far as I can tell, there is practically no one defending this Kaufmann aerosol hypothesis.

It would be interesting to know if Kaufmann himself still believes it. And it would be interesting to know if Hansen - who argued even more implausibly for volcanic aerosols as the explanation - still believes his theory. These are the only two scientists of any note who I am aware of who consider an aerosol hypothesis to be plausible.

> 4) The AR5 Fig. 7.17 shows that the net aerosol forcing from 75 - 90
> degrees N is positive, rising to a maximum of 0.2 W m-2 at the N. Pole.
> Chung and Räisänen 2011 GRL (following Chung, Ramanathan et al. 2005 JGR)
> find a maximum of 0.5 W m-2 at around 80 degrees N and about 0.3 W m-2 at
> the N. Pole. These authors consider three possible explanations for the
> larger than expected Arctic amplification:
>
> i) model feedbacks are too large in the tropics (i.e. the Lindzen theory).
> ii) the model feedbacks are too small in the Arctic (e.g. the snow/ice
> feedback).
> iii) the aerosol forcing is exaggerated in the tropics and warming is
> underestimated in Arctic.
>
> It follows from this and also from common sense that any belief that the

> aerosol forcing is *underestimated* at low latitudes creates an even bigger

> problem when trying to explain observed Arctic amplification relative to
> the tropics. Do we agree?

As a side note, I find it very surprising that you lend such credence to the models that are trying to backfit the temperature curves, and doing such a poor job of it. The arctic amplification is happening very rapidly now, the collapse of sea ice--indeed, as Dr. Stroeve says, a "new climate state" is going to require a significant reworking of the climate models over the next few years. I also expect a very real "mea culpa" from those modelers who have allowed us to get to this point in our development, literally teetering on the brink of complete societal and cultural collapse.

See my comments above; I don't give too much credence to the models. But it's one thing to say that the state of the art models are likely to be wrong, and another to conclude - "ah some simple energy balance model must be better".

He has a cute theory of how rapidly the ice albedo will be compensated for in the autumnal/winter cycle. The rapid collapse of multi-year sea ice (and the lack of recovery this year after last years melt) is showing this theory to be incorrect.

It's not a 'cute theory'; it's a state of the art AOGCM. The ECHAM5 is hardly a 'cute theory'. Meanwhile, this is not correct. We have observed the fastest recovery of sea ice after 2012 in the history of the satellite observations.

It is a good conceptual idea, I am not saying that there won't be some recovery along the way. Especially if the conveyor current collapses. Then we will see a large recovery in sea ice. However,

You are confusing 2008 data with 2011 data, and you are confusing the models for the timing of the loss if sea ice in the arctic and models that are attempting to describe the effects that will be induced by that ice loss. They are different models.

> 6) You have made a lot of the Eisenman and Wettlaufer 2008 PNAS paper that
> presents a simplified model of the Arctic that does indeed exhibit 'tipping
> points'. This model, however, doesn't include carbon cycle feedbacks - the
> tipping points in the model are caused primarily by the ice-albedo
> feedback. I have speculated that if this model was correct, we would
> expect to see periods of perennial ice free Arctics in the Earth's very
> ancient prehistory. Each time the Arctic melts it should get stuck in this
> state until there is a massive cooling to get it out again. I am not aware
> that any such state is observed in the paleoclimate record. What do you
> say to this?

what I said from the beginning, the carbon cycle feedbacks occurred over such a slow period during the Eemian, that the 200-300% higher density of terrestrial carbonaceous plant matter was able to respond to them and maintain CO2 levels at or below 290ppmv.

Therefore, all of the warming (2C in the latter period of the Eemian) was associated with non-carbon feedbacks.

To consider why things are different today you have to consider that,

a) The sun has grown in its intensity since 110,000 BP
b) we have added an additional 105PPMv of CO2 and 850PPbv CH4 as compared to the Eemian
c) we are going to raise the temperature into the Eemian range within 200 years when it took the Eemian 5,000 years to do the same.
d)land use characteristics have significantly reduced negative carbon cycle effects that might occur during the 200 year warming cycle.

That is, basically, why the earlier cycles do not show the 10'K warming signal after the ice melts in the arctic. It happened so slowly that, once the ice was gone, the amount of ancient redwoods in the arctic and 20 foot ferns in the Antarctic sucked up all the carbon and plunged the world back into an ice age.

Look, I brought up the Eemian simply because there was a summer ice-free Arctic and you'd think, a fully engaged ice-albedo feedback. It is impossible in general to argue from the Eemian that it tells us something about the climate sensitivity today. The reasons for this are - (1) the Eemian earth was simply a different earth. The climate sensitivity at the Eemian is highly unlikely to be the same as the climate sensitivity in the present interglacial. (2) our knowledge of the actual global average temperature is nothing much more than guesswork. You say the global average temperature rose 2 K - how do we know this? Is it a GCM result?

This paper has essentially shown that all efforts to constrain climate sensitivity from paleoclimate studies using the delta T = G * delta Q relationship are (my opinion) nothing more than wishful thinking.

> 7) On carbon cycle feedbacks - these feedbacks if they are important will> operate by adding to the well-mixed greenhouse gases. As such, they will
> operate in the global average and will not be localised in the Arctic.
> Thus, for carbon cycle feedbacks to be important in the Arctic, they need
> to be very large - they need to raise the global average forcing quite a
> bit. Do we agree?

I don't think that carbon cycle feedbacks are important to consider for the arctic. The ice is going to be gone by 2027, remember?

Yes I do remember - okay, agreed.

I appreciate your summary, I don't think that you have adequately responded to my points at all. I do appreciate your work to attempt to consolidate the discussion. We were ranging far and wide there.

You're welcome.

In summary:

The PIOMAS data has been confirmed, we will have an ice free summer by 2027 and likely earlier.

Um, confirmed? By a climate change activist working at the Discovery Channel...are you serious?

What am I supposed to respond to or comment on here? The PIOMAS data? I don't dispute the PIOMAS data, if that's what you want to hear.

I dispute your unargued inference that a few years of larger than expected sea ice retreat implies in the absence of any other data or theory that a summer ice free Arctic is due in 2027. It is essentially - as far as I can see - a completely circular argument. Or, in fact, not an argument at all. You simply assume this is true without offering any argument at all. It's obvious, you say - all you have to do is look at the PIOMAS data.

I then keep then pointing out that the models predict a decline that looks like Tietsche et al. Fig. 1, and not a linear decline, and your only response is that you know that the models are wrong. The way you have presented the theory to me suggests it is essentially just dogma.

The arctic albedo effect will produce a 5-7C additional warming above the current arctic amplification, during ice-free periods, as shown in the models that are running through my brain.

The supplanting of our "normal" mid-latitude weather patterns for the hellish new reality that we will be forced to deal with in a few short years are based on an increase in tropical evaporation and thunderstorm activity, coupled with an arctic amplification induced weakening of the polar jet, allowing for standing waves that will solidify droughts in grain producing regions and floods in populated regions.

The effects of current, locked-in greenhouse gas induced warming for current concentration levels will be at least another (yes, beginning today) 2'C warming from todays levels.

With arctic albedo effects and carbon cycle feedbacks that will occur, we have absolutely no option but to radically decarbonize our economies AND develop carbon capture and sink technologies to extract GHG from the atmosphere (above current natural sinks).

I am trying to show you that this reasoning is simply leading you to impossible conclusions, reductio ad absurdum. Something is obviously wrong in your assumptions. I'm actually not sure what you're doing wrong.

when the Eemian temperature was similar to today's experience, with a melting ice cap and global temperatures similar to today's pre-industrial, the Eemian had 2K more to climb before it reached its apex. (last 5,000 years of Eemian) Milankovitch forcing during the last 5 thousand years of the Eemian are inconsequential so disregard it. The total forcing from CO2 during the Eemian was also negligible since CO2 and CH4 only rose imperceptibly during the last 5,000 years.

The only drivers during this period of the Eemian were aerosol and albedo.

Well, that assumption is obviously impossible. Aerosols cause cooling - what are we left with - massive internal variability? Have you got the CO2 concentrations wrong? Something's wrong, because your argument ostensibly supports Lindzen (1993; Nature) - that paleoclimate simply tells us nothing at all that's sensible about the climate sensitivity.

So, include those in our current model. They are already expected to occur naturally due to increased desertification (aerosols) and ice cap loss (albedo)

Then add to that the forcing from our higher CO2 and CH4 values, then include the rapid-response carbon cycle forcings without the slow-response carbon cycle captures that were in play during the Eemian and consider future anthropogenic emission.

So on top of Eemian derived 2K additional warming add the forcing from Anthropocene CO2 and CH4 values (+110PPMv and 850PPBv respectively) and then consider the carbon cycle responses.

I already suggested that the Eemian-derived equilibrium response would be around 5-7C of warming from pre-industrial, not 30.

You asserted that the Eemian-derived response is around 5-7 C but gave no reasoning. I am showing you, using the standard equation for the earth's global energy balance, that your numbers imply a sensitivity of around (actually) 120 K/doubling of CO2. You have practically no global average forcing and a massive temperature increase. It ain't makin' sense!

As is unfortunately often the case, you seem to be making up numbers out of thin air and not providing any references or reasoning. While I don't think delta T = G * delta Q is particularly reliable it's also not so bad that it would get the sensitivity wrong by around 100 K. So, the numbers you're throwing around are obviously wrong.

Mitchell J

Alex, still, you completely misunderstood what I was saying, or intentionally took it ... read on. ... you apparently do not yet even follow the reasoning,

Message 3 of 20
, Mar 9 1:25 PM

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Alex, still, > > you completely misunderstood what I was saying, or intentionally took it

> > out of context.

> >
> > first off, The milankovitch driven .25 W m-2 is from the beginning to the
> > end of the Eemian, so you would need T = 8K but that is not at all what I
> > am saying so forget milankovitch completely.
> >
>
> That would make the situation even worse.
>
> delta T = G * delta Q, 8 = G * 0.25, G = 32; For Q(2xC02) =~ 3.7,
> ECS(Eemian) = 32 * 3.7 = 118 K/doubling of CO2.

read on.

>
> I am trying to show you that this reasoning is simply leading you to
> impossible conclusions, *reductio ad absurdum*. Something is obviously
> wrong in your assumptions. I'm actually not sure what you're doing wrong.
>

you apparently do not yet even follow the reasoning, and have resorted to straw man argument defense.

>
> >
> > when the Eemian temperature was similar to today's experience, with a
> > melting ice cap and global temperatures similar to today's pre-industrial,
> > the Eemian had 2K more to climb before it reached its apex. (last 5,000
> > years of Eemian) Milankovitch forcing during the last 5 thousand years of
> > the Eemian are inconsequential so disregard it. The total forcing from CO2
> > during the Eemian was also negligible since CO2 and CH4 only rose
> > imperceptibly during the last 5,000 years.
> >
> > The only drivers during this period of the Eemian were aerosol and albedo.
> >
>
> Well, that assumption is obviously impossible. Aerosols cause cooling -

>
>
> > So, include those in our current model. They are already expected to occur
> > naturally due to increased desertification (aerosols) and ice cap loss
> > (albedo)
> >
> > Then add to that the forcing from our higher CO2 and CH4 values, then
> > include the rapid-response carbon cycle forcings without the slow-response
> > carbon cycle captures that were in play during the Eemian and consider
> > future anthropogenic emission.
> >
>
> > So on top of Eemian derived 2K additional warming add the forcing from
> > Anthropocene CO2 and CH4 values (+110PPMv and 850PPBv respectively) and
> > then consider the carbon cycle responses.
> >
> > I already suggested that the Eemian-derived equilibrium response would be
> > around 5-7C of warming from pre-industrial, not 30.
> >
>

> You *asserted *that the Eemian-derived response is around 5-7 C but gave no
> reasoning.

Yes, yes I did on several occasions.

When, (AND IF) you choose to actually respond to my point use the following:

Two degrees K warming at the end of the Eemian can be reasonably attributed to the Aerosol and Albedo Forcing, and is analogous to what we are currently expecting for our own polar ice cap loss and increased desertification.

We then have an increased forcing from the Eemian that is due to the current 110ppmv CO2 and 850ppmv CH4 -- The increased forcing from these gasses is approximately equivalent to the increased forcing from pre-industrial era, this value is +2.83 W m-2, this is forcing above that experience during the Eemian.

Then we have the potential for future carbon cycle feedbacks that will not be compensated for by the slow terrestrial response. (you have already suggested .2C by 2100 as a low-end estimate for this value)

What is the final value, above the Eemian derived Aerosol and Albedo 2C increase from pre-industrial levels that you would expect?

I am showing you, using the standard equation for the earth's

> global energy balance, that your numbers imply a sensitivity of around
> (actually) 120 K/doubling of CO2. You have practically no global average
> forcing and a massive temperature increase. It ain't makin' sense!

That is because (I suspect) you are intentionally clouding the discussion.

>
> As is unfortunately often the case, you seem to be making up numbers out of
> thin air and not providing any references or reasoning. While I don't
> think delta T = G * delta Q is particularly reliable it's also not so bad
> that it would get the sensitivity wrong by around 100 K. So, the numbers
> you're throwing around are obviously wrong.
>

only in your twisted, made up, strawman argument game where you attribute values and statements to me that are not my own and then discount (or simply fail to acknowledge) that I have stated repeatedly that those are not my values and not what I am saying at all.

(recall you used a .25W m-2 milankovitch cycle value to get your 100k value. When the .25W m-2 value is well documented, but you are not taking into account the natural feedback mechanisms of the Eemian which I have stated from the beginning were large (and already present in our current Holocene climate).

Alex Harvey

John, Take a deep breath - I have better things to do in my spare time than cloud this discussion about the Eemian. 1) *Methods for inferring climate

Message 4 of 20
, Mar 9 9:40 PM

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John,

Take a deep breath - I have better things to do in my spare time than cloud this discussion about the Eemian.

There are basically two ways you can estimate climate sensitivity from paleoclimate observations:

a. Use the formula delta T = G * delta Q - this is called "paleocalibration".

b.
Compare known observations of paleoclimate data with GCM simulations.
This is called "paleoclimate modelling". There are many variations on
the paleoclimate modelling approach, but you need access to GCMs.

Since neither you nor I have access to a GCM the only method we can use is paleocalibration.

Our
communication difficulty appears to arise because you seem to believe
you can infer the climate sensitivity without knowing anything about the
total radiative forcing - which is absurd. Either that, or you have a
value for the total radiative forcing in mind, and you are not telling
me what you think it is. So, I think it's more likely you are confused.

2) Natural aerosols cause cooling not warming.

You claimed that natural aerosols cause warming, and not cooling.

I
note that in doing so you seem to exclude volcanic sulfur dioxide
emissions from your definition of "natural aerosols". That's a bit
puzzling. Does that mean you don't think there were no volcanoes during
the Eemian period?

But even if I go along with this definition of "natural aerosols" it's still completely wrong.

Sea salt aerosols play a dual role in affecting the atmospheric
radiative balance. Directly, sea salt particles scatter the incoming
solar radiation and absorb the outgoing terrestrial radiation. By acting
as cloud condensation nuclei, sea salt aerosols indirectly modulate the
atmospheric radiative budget through their effective contribution to
cloud formation. Using the Canadian Aerosol Module (CAM)–Canadian Centre
for Climate Modelling and Analysis (CCCma) GCM, version 3 (GCM3)
framework, the direct as well as the indirect shortwave (SW) radiative
effects of sea salt aerosols are simulated. The model results herein
suggest that sea salt aerosols exert a significant direct radiative
effect over oceanic regions, with seasonal means in the range from −2 to
−3 W m−2 over the Southern Ocean. Globally, sea salt’s SW indirect effect (annual mean −0.38 W m−2) is found to be less than its direct effect (annual mean −0.65 W m−2).
However, sea salt’s indirect effect is found to be far stronger over
the Southern Hemisphere than over the Northern Hemisphere, especially
over the Southern Ocean with seasonal means around −4 W m−2,
which exceed its direct effect. The model results herein suggest that
sea salt aerosols significantly modulate the atmospheric radiation
budget over oceanic regions and need to be accounted for in global
climate models.

Dust

For dust you can go to AR5 table 7.1 and see that the RFari value for "dust (not necessarily anthropogenic)" is given to be
–0.1 (–0.3 to +0.1) W m-2. So dust also causes cooling in the global average.

3) Is the ice albedo a feedback or a forcing?

I
was assuming we regarded the ice-albedo change as a fast feedback - but
maybe you are right here? Depending on exactly what the timeframe is
and exactly which ice sheets you are referring to - maybe I should
consider this a forcing? Okay, happy to concede this. Except, you need
to tell me what you think the value of the forcing is.

4) Kaspar et al. 2005 GRL.

I
got fed up and decided to find out what the consensus is on the Eemian
interglacial and confirmed what I suspected - that the difference in
Eemian climate is thought to be a result of simply a completely
different distribution of warming and nothing much to do with a different global average temperature.

As
such your claim that the "temperature rose by 2K" is probably simply
wrong. You are probably confusing a regional temperature difference
with the global average.

[15] After approximately 1000 simulated years, the simulationsof the Eemian and the preindustrial climate becamestable, i.e. quasi-stationary with respect to oceanic overturning
circulation and sea ice extent. For the analysis wecalculated the mean climate of an arbitrarily selected50 years interval starting 1200 years after the beginningof both simulations. Selecting different periods does not
change the results. The following description of generalfeatures focuses on differences between the Eemian and thepreindustrial climate on the Northern Hemisphere.[16] The model responds with a slightly higher global
mean temperature in the Eemian than in the preindustrialsimulation.

Typically,
the only way you can end up with higher global average temperatures is
to assume a higher global average forcing. This usually means higher
CO2 concentrations. If you are willing to believe this sort of
simplistic thinking.

As I say, Michel Crucifix's paper appears to
have driven a big hole through the heart of such simplistic thinking,
and the objections put forward by Lindzen is 1993 (Nature) are starting
to look a whole lot more sensible. As such, experts on paleoclimate
sensitivity (e.g. James Annan and Julia Hargreaves) are now saying that
remote climate periods really don't tell us anything about climate
sensitivity.

Alex, still, > > you completely misunderstood what I was saying, or intentionally took it

> > out of context.

> >
> > first off, The milankovitch driven .25 W m-2 is from the beginning to the
> > end of the Eemian, so you would need T = 8K but that is not at all what I
> > am saying so forget milankovitch completely.
> >
>
> That would make the situation even worse.
>
> delta T = G * delta Q, 8 = G * 0.25, G = 32; For Q(2xC02) =~ 3.7,
> ECS(Eemian) = 32 * 3.7 = 118 K/doubling of CO2.

read on.

>
> I am trying to show you that this reasoning is simply leading you to

you apparently do not yet even follow the reasoning, and have resorted to straw man argument defense.

>
> >
> > when the Eemian temperature was similar to today's experience, with a
> > melting ice cap and global temperatures similar to today's pre-industrial,
> > the Eemian had 2K more to climb before it reached its apex. (last 5,000
> > years of Eemian) Milankovitch forcing during the last 5 thousand years of
> > the Eemian are inconsequential so disregard it. The total forcing from CO2
> > during the Eemian was also negligible since CO2 and CH4 only rose
> > imperceptibly during the last 5,000 years.
> >
> > The only drivers during this period of the Eemian were aerosol and albedo.
> >
>
> Well, that assumption is obviously impossible. Aerosols cause cooling -

>
>
> > So, include those in our current model. They are already expected to occur
> > naturally due to increased desertification (aerosols) and ice cap loss
> > (albedo)
> >
> > Then add to that the forcing from our higher CO2 and CH4 values, then
> > include the rapid-response carbon cycle forcings without the slow-response
> > carbon cycle captures that were in play during the Eemian and consider
> > future anthropogenic emission.
> >
>
> > So on top of Eemian derived 2K additional warming add the forcing from
> > Anthropocene CO2 and CH4 values (+110PPMv and 850PPBv respectively) and
> > then consider the carbon cycle responses.
> >
> > I already suggested that the Eemian-derived equilibrium response would be
> > around 5-7C of warming from pre-industrial, not 30.
> >
>

> You *asserted *that the Eemian-derived response is around 5-7 C but gave no
> reasoning.

Yes, yes I did on several occasions.

When, (AND IF) you choose to actually respond to my point use the following:

Two degrees K warming at the end of the Eemian can be reasonably attributed to the Aerosol and Albedo Forcing, and is analogous to what we are currently expecting for our own polar ice cap loss and increased desertification.

We then have an increased forcing from the Eemian that is due to the current 110ppmv CO2 and 850ppmv CH4 -- The increased forcing from these gasses is approximately equivalent to the increased forcing from pre-industrial era, this value is +2.83 W m-2, this is forcing above that experience during the Eemian.

Then we have the potential for future carbon cycle feedbacks that will not be compensated for by the slow terrestrial response. (you have already suggested .2C by 2100 as a low-end estimate for this value)

What is the final value, above the Eemian derived Aerosol and Albedo 2C increase from pre-industrial levels that you would expect?

I am showing you, using the standard equation for the earth's
> global energy balance, that your numbers imply a sensitivity of around
> (actually) 120 K/doubling of CO2. You have practically no global average
> forcing and a massive temperature increase. It ain't makin' sense!

That is because (I suspect) you are intentionally clouding the discussion.

>
> As is unfortunately often the case, you seem to be making up numbers out of
> thin air and not providing any references or reasoning. While I don't
> think delta T = G * delta Q is particularly reliable it's also not so bad
> that it would get the sensitivity wrong by around 100 K. So, the numbers
> you're throwing around are obviously wrong.
>

only in your twisted, made up, strawman argument game where you attribute values and statements to me that are not my own and then discount (or simply fail to acknowledge) that I have stated repeatedly that those are not my values and not what I am saying at all.

(recall you used a .25W m-2 milankovitch cycle value to get your 100k value. When the .25W m-2 value is well documented, but you are not taking into account the natural feedback mechanisms of the Eemian which I have stated from the beginning were large (and already present in our current Holocene climate).

Mitchell J

Alex, Questions: 1) From your study did you find that the Eemian period had an ice free arctic? 2) Do you now assert that this ice free state is due to a

Message 5 of 20
, Mar 10 12:41 PM

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Alex,

Questions:

1) From your study did you find that the Eemian period had an ice free arctic?

2) Do you now assert that this ice free state is due to a regional temperature difference and not a globally averaged one?

3) What do you believe was the globally average temperature at the end (peak) of the Eemian? How does this average temperature compare with the increase of temperature associated with our most recent rise from the last glacial? (note: this value is generally accepted to be about 6K)

4) Do you agree that the relative forcing value between the Eemian and the last interglacial were the same for the identical difference in globally averaged temperature rise? (last interglacial compared to the Eemian period just prior to Eemian Arctic Melt -EAM)

5) You asked me why we did not experience a massive runaway warming event after the EAM. This occurred during the last 5,000 years of the Eemian. I stated that the 5,000 year period allowed for significant global compensation to the carbon cycle changes that occurred by this 2'C rise over this period.

I then asked you, (and am waiting for a response) if the temperature difference (and forcings) were identical for the last interglacial and the period leading to the EAM) and the current additional forcings due to anthropogenic emissions have resulted in an additional 2.83 w m-2 AND we will not have the benefit of natural compensations to carbon cycle changes, what do you expect to be the final globally averaged equilibrium temperature from our current CO2 ppmv after the arctic melts?

6) what do you estimate to be the final equilibrium temperature once we reach 800ppmv co2?

-----------------
With regard to Eemian aerosols, ok yes they were negative, the difference from cooler to warmer temperatures was also likely an increasing negative forcing. Since temperatures continued to rise, in absence of CO2 and Solar forcing (assuming volcanic activity was steady state) the only reasonable variable is Albedo which caused the remaining warming.

Alex Harvey

On 11 March 2013 06:41, Mitchell J wrote: Alex, ... I am not here to parade as some expert on the Eemian. But, yes, I do know that the

1) From your study did you find that the Eemian period had an ice free arctic?

I am not here to parade as some expert on the Eemian. But, yes, I do know that the Eemian had an ice free Arctic.

2) Do you now assert that this ice free state is due to a regional temperature difference and not a globally averaged one?

Actually I assert that the data is so uncertain that no one has a clue. We have had published global average temperature anomalies at the LGM - where the data is much, much better - range from as low as 1 K to as high as 6 K.

As you can see from the RealClimate article I posted, we have only just for the first time succeeded in extracting Eemian ice from Greenland ice cores. Knowledge of the Eemian is most uncertain.

3) What do you believe was the globally average temperature at the end (peak) of the Eemian? How does this average temperature compare with the increase of temperature associated with our most recent rise from the last glacial? (note: this value is generally accepted to be about 6K)

John, I am getting very tired of you plucking these numbers out of thin air without any effort at justifying them. It is, if nothing else, extremely arrogant of you to make these appeals to your own authority and expect me to have to always assume for the sake of argument that your numbers make sense - especially given the number of times in the discussion I've found your numbers were completely wrong. If you want me to believe that there was a "generally accepted" temperature increase of 6 K at the Eemian, it would be pretty trivial for you to show me a published paper that says this. Please do so.

My belief is no one has a clue what the global average temperature was at any stage of the Eemian.

4) Do you agree that the relative forcing value between the Eemian and the last interglacial were the same for the identical difference in globally averaged temperature rise? (last interglacial compared to the Eemian period just prior to Eemian Arctic Melt -EAM)

In so far as no one knows whether there was an identical globally averaged temperature rise, and no one knows accurately what the forcing was, then clearly, no, I don't buy into this simplistic thinking.

5) You asked me why we did not experience a massive runaway warming event after the EAM. This occurred during the last 5,000 years of the Eemian. I stated that the 5,000 year period allowed for significant global compensation to the carbon cycle changes that occurred by this 2'C rise over this period.

Yes I asked you this. If Greenland temps were 8 K greater than present (as I've seen claimed) I find it hard to believe that the Arctic temps didn't reach a critical threshold and melt away into a perennial ice free Arctic and get stuck there for thousands of years. But this is just an intuition, and you can take it with a grain of salt.

The harder objection I have raised, and which you continue to ignore, is how come there is not evidence anywhere in the entire paleo record of protracted periods of ice free Arctic that you would expect if such critical thresholds existed?

I then asked you, (and am waiting for a response) if the temperature difference (and forcings) were identical for the last interglacial and the period leading to the EAM) and the current additional forcings due to anthropogenic emissions have resulted in an additional 2.83 w m-2 AND we will not have the benefit of natural compensations to carbon cycle changes, what do you expect to be the final globally averaged equilibrium temperature from our current CO2 ppmv after the arctic melts?

Once again, I completely reject your assumptions. That's why I'm not going to answer your questions about the implications of these assumptions.

Once you are on this timescale then you need to consider forcing from plate tectonics and differences in continental configuration, and not to mention differences in the biosphere. It was a completely different Earth. My view is it tells us absolutely nothing of interest at all. This is also the opinion of most experts.

6) what do you estimate to be the final equilibrium temperature once we reach 800ppmv co2?

As above, this entire discussion is a waste of time.

If you are sincere about estimating climate sensitivity from paleo observations, I am curious to know why you are not discussing the LGM where actual data exists? Most serious attempts to estimate climate sensitivity from paleorecord use the LGM. I'd like to know why you don't want to use the LGM as well? Is it because the data implies a low climate sensitivity of around 2 K?

Alex Harvey

John, Further to this I have a review paper on the history of estimations of climate sensitivity. Tamsin L. Edwards, Michel Crucifix and Sandy P. Harrison,

Message 7 of 20
, Mar 10 11:46 PM

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John,

Further to this I have a review paper on the history of estimations of climate sensitivity.

IV Using the palaeorecordThe geological record includes times whenthe change in forcing and the climate responsewere large compared with the changes ofthe recent past or those expected as a resultof doubling CO2. The pre-instrumental orpalaeorecord thus provides a strong testof how well we understand and can modeldifferent climates, and an opportunity toestimate climate sensitivity in radically differentclimates. For the most recent glacialinterglacialcycles, the ice core record (eg,EPICA community members, 2004) providesdirect information on global atmosphericGHG concentrations and isotopic measurementsof Antarctic surface temperatures.Climates in other eras and in other regionsare reconstructed from chemical, isotopic,sedimentological or biological data whichreflect the response of these ‘sensors’ toclimate change. However, our knowledge ofthe climate response to changes in forcing onpalaeo-timescales is necessarily less precisethan in modern climates, because of thenature of the records and the patchiness ofthe spatial coverage.1 Inferring climate sensitivity directly frompalaeodataJust as for modern climates, inferring climatesensitivity from palaeodata records requiresestimates of the forcings, the temperatureresponse and the heat uptake by the ocean.However, the rate of ocean heat uptake isusually treated as negligible as it is assumedthe ocean is at, or close to, equilibrium, so onlyΔTpalaeo and Qpalaeo are required (Equation 1).Estimates of climate sensitivity have beenmade based on three geological periods: theMid-Cretaceous (Hoffert and Covey, 1992;Barron, 1993), the early Eocene (Coveyet al., 1996) and the Last Glacial Maximum(Hoffert and Covey, 1992; Hansen et al.,1993).

As of 2007, no one had ever tried to use the Eemian interglacial to estimate climate sensitivity.

But an up to date paper is the somewhat controversial 'Paleosense, 2012, Nature' paper that is going to be cited in the AR5:

- a look in general at glacial cycles, that attempt to improve upon observations of the LGM-Holocene transition by studying data from the entire Pleistocene period.

- early to middle Pliocene

- Miocene Optimum

- Eocene-Oligocene transition

- Late Eocene-Middle Eocene Climatic Optimum

- PETM

- Phanerozoic.

So, still no one appears to have tried to use the Eemian to estimate climate sensitivity.

But this paper is important in that in includes the following caveat (noted in the text, but not considered in their method):

We emphasize that all feedbacks, and thus the calculated climatesensitivity, may depend in a—largely unknown—nonlinear manner
on the state of the system before perturbation (the ‘background climatestate’) and on the type of forcing7–15. The relationship of S with backgroundclimate state differs among climate models12,16–18. A suggestion
of state dependence is also found in a data comparison (Table 2)6, whereclimate sensitivity for the past 800,000 years (800 kyr) shows substantialfluctuations through time (Fig. 2). In contrast, its values for the Last
Glacial Maximum (LGM) alone occupy only the lower half of that range(Fig. 2). That evaluation also suggests that the relationship of S with thegeneral climate state may not be simple.

And what is S? Glad you asked! Earlier -

We introduce the more general definition of the ‘climate sensitivityparameter’ as the mean surface temperature response to any radiativeperturbation (S=DT/DR; where DT and DR are centennial to multimillennial
averages), which facilitates comparisons between studiesfrom different time-slices in Earth history. For brevity, we refer to S as‘climate sensitivity’. In the definition of S, an initial perturbation DR0leads to a temperature response DT0 following the Stefan–Boltzmann
law, which is the temperature-dependent blackbody radiation response.This is often referred to as the Planck response4, with a value S0 of about0.3KW21m2 for the present-day climate5,6

So Sis a new notation for the climate sensitivity parameter. It is a replacement for G (or sometimes lamda).

Why did we need one?

It's kind of funny, because our knowledge has converged on the understanding that climate sensitivity does depend in "a—largely unknown—nonlinear manner on the state of the system before perturbation (the ‘background climate state’) and on the type of forcing7–15".

This result leads to the disappointing conclusion that there is no single value for climate sensitivity that can be inferred from paleodata and due to hte "largely unknown, nonlinear" relationship with the climate sensitivity in the present interglacial, there is simply no way of using remote paleoclimate periods to tell us about the climate sensitivity in the present. The only way we can do that is to pretend - which is what the authors do - that S does scale linearly with G. Clever.

Anyway, if you now forget that S is related in an unknonwn, nonlinear manner to G, you can go to Paleosense, Fig 2, you'll see how these authors determined that climate sensitivity itself varied over time.

So, they've got the ECS way too high at the LGM. How did they do this? Easy, they just averaged over all studies - including old studies like Lea, 2004 that used a value for LGM cooling that is known to be way too high.

Then, bringing this back to the Eemian, you can see that at 120000BP S =~ 1.1 K W-1 m2 = 4.07 K / 2xCO2.

To me, this is all sticking your finger in the air stuff.

Mitchell J

... Actually it is 8K at the Dome C ice core. If you think that the earth could go from a deep ice-age to an ice-free arctic state with only 1K of average

Message 8 of 20
, Mar 11 9:48 AM

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> > 2) Do you now assert that this ice free state is due to a regional
> > temperature difference and not a globally averaged one?
> >
> Actually I assert that the data is so uncertain that no one has a clue. We
> have had published global average temperature anomalies at the *LGM* -
> where the data is much, much better - range from as low as 1 K to as high
> as 6 K.
>

Actually it is 8K at the Dome C ice core.

If you think that the earth could go from a deep ice-age to an ice-free arctic state with only 1K of average temperature change (Eemian) then we have nothing left to talk about. You do not have a clue.

> As you can see from the RealClimate article I posted, we have only just for
> the first time succeeded in extracting Eemian ice from Greenland ice
> cores. Knowledge of the Eemian is most uncertain.

that is such a bunch of nonsense I don't think it warrants a response.

>
> > 3) What do you believe was the globally average temperature at the end
> > (peak) of the Eemian? How does this average temperature compare with the
> > increase of temperature associated with our most recent rise from the last
> > glacial? (note: this value is generally accepted to be about 6K)
> >
> John, I am getting very tired of you plucking these numbers out of thin air
> without any effort at justifying them. It is, if nothing else, extremely
> arrogant of you to make these appeals to your own authority and expect me
> to have to always assume for the sake of argument that your numbers make
> sense -

6K from the depth of the last ice age to the beginning of the Holocene is a trivial number--easily verified and well accepted. This is the value I have asserted. Contrary to your comprehensions.

>

> > 5) You asked me why we did not experience a massive runaway warming event
> > after the EAM. This occurred during the last 5,000 years of the Eemian. I
> > stated that the 5,000 year period allowed for significant global
> > compensation to the carbon cycle changes that occurred by this 2'C rise
> > over this period.
> >
> Yes I asked you this. If Greenland temps were 8 K greater than present (as
> I've seen claimed) I find it hard to believe that the Arctic temps didn't
> reach a critical threshold and melt away into a perennial ice free Arctic
> and get stuck there for thousands of years.

But the probably did. . .for at least a few (2-3) thousand years

This is a blink of an eye in time compared to temperature record provided by the dome C sample.

for the very last time. The reason that we didn't get "stuck" there is because temperatures rose only a few degrees over the course of thousands of years, this allowed the natural environment (flora) in on the earths surface and in the oceans to readily absorb the carbon emitted into the atmosphere. This is why there is no massive runup in carbon dioxide during this time.

> The harder objection I have raised, and which you continue to ignore, is *how
> come there is not evidence anywhere in the entire paleo record of
> protracted periods of ice free Arctic that you would expect if such
> critical thresholds existed?*

The record indicates that these periods do happen but the increased flora development of several thousands of years in the arctic and Antarctic regions (as well as subsea growth) creates a massive decarbonization response, over the course of a few thousand years, which then leads to a collapse in average global temperatures and plunges the earth into a new ice age.

Your assertion that there is *no* record of *protracted* (what is several thousand years not long enough for you?) period of ice free arctic periods. (what do you know about the PETM?)

> If you are sincere about estimating climate sensitivity from paleo
> observations, I am curious to know why you are not discussing the LGM where
> actual data exists? Most serious attempts to estimate climate sensitivity
> from paleorecord use the LGM. I'd like to know why you don't want to use
> the LGM as well? Is it because the data implies a low climate sensitivity
> of around 2 K?
>

--keep it up alex, go right ahead, stand by Lindzen and all the other industry financed deniers. You will be proven worse than irrelevant in the near future. I hope that you grow a conscience in the near future.

Just remember, you were the one who was asking about the response mechanism from the paleo regarding a melting ice cap. To that end I have responded more than adequately. You're lack of ability to even consider the fact that this happened during the Eemian with CO2 levels that approximated the pre-industrial shows just how irrelevant you actually are.

> > 2) Do you now assert that this ice free state is due to a regional
> > temperature difference and not a globally averaged one?
> >
> Actually I assert that the data is so uncertain that no one has a clue. We

> have had published global average temperature anomalies at the *LGM* -

> where the data is much, much better - range from as low as 1 K to as high
> as 6 K.
>

Actually it is 8K at the Dome C ice core.

Okay, so 8 K at Dome C. Tells me nothing about the global average.

If you think that the earth could go from a deep ice-age to an ice-free arctic state with only 1K of average temperature change (Eemian) then we have nothing left to talk about. You do not have a clue.

> As you can see from the RealClimate article I posted, we have only just for> the first time succeeded in extracting Eemian ice from Greenland ice
> cores. Knowledge of the Eemian is most uncertain.

that is such a bunch of nonsense I don't think it warrants a response.

Huh? RealClimate is publishing nonsense? Or what's your point?

> > 3) What do you believe was the globally average temperature at the end
> > (peak) of the Eemian? How does this average temperature compare with the
> > increase of temperature associated with our most recent rise from the last
> > glacial? (note: this value is generally accepted to be about 6K)
> >
> John, I am getting very tired of you plucking these numbers out of thin air
> without any effort at justifying them. It is, if nothing else, extremely
> arrogant of you to make these appeals to your own authority and expect me
> to have to always assume for the sake of argument that your numbers make
> sense -

6K from the depth of the last ice age to the beginning of the Holocene is a trivial number--easily verified and well accepted. This is the value I have asserted. Contrary to your comprehensions.

Oh...so now you mean 6 K is the rise from the "depth of the last ice age" - you mean the LGM? Okay, so you are using a value that is known to be too high. Your value comes from:

This value was always way too high and has been refuted. Please refer to the Annan and Hargreaves I posted in the other thread - the actual value is likely to be closer to 4 K.

> The harder objection I have raised, and which you continue to ignore, is *how

> come there is not evidence anywhere in the entire paleo record of
> protracted periods of ice free Arctic that you would expect if such

> critical thresholds existed?*

The record indicates that these periods do happen but the increased flora development of several thousands of years in the arctic and Antarctic regions (as well as subsea growth) creates a massive decarbonization response, over the course of a few thousand years, which then leads to a collapse in average global temperatures and plunges the earth into a new ice age.

Your assertion that there is *no* record of *protracted* (what is several thousand years not long enough for you?) period of ice free arctic periods. (what do you know about the PETM?)

I'll have a look.

> If you are sincere about estimating climate sensitivity from paleo> observations, I am curious to know why you are not discussing the LGM where
> actual data exists? Most serious attempts to estimate climate sensitivity
> from paleorecord use the LGM. I'd like to know why you don't want to use
> the LGM as well? Is it because the data implies a low climate sensitivity
> of around 2 K?
>

--keep it up alex, go right ahead, stand by Lindzen and all the other industry financed deniers. You will be proven worse than irrelevant in the near future. I hope that you grow a conscience in the near future.

WTF has this got to with Lindzen? Lindzen has never attempted to estimate climate sensitivity from paleoclimate because he believes it is a fool's game. It is the entire field of paleoclimatology that uses the LGM primarily to estimate climate sensitivity.

Just remember, you were the one who was asking about the response mechanism from the paleo regarding a melting ice cap. To that end I have responded more than adequately. You're lack of ability to even consider the fact that this happened during the Eemian with CO2 levels that approximated the pre-industrial shows just how irrelevant you actually are.

John, you've started frothing at the mouth again and it's not a good look. If you tell me what you think:

1) the time frame of interest is in years BP to years BP
2) what you think the total radiative forcing is for that period and how you arrived at this number3) what you think the change in global average temperature is and how you arrive at this number

We can discuss this.

Mitchell J

... 115,000BP to 110,000BP -- I have stated this on several occasions. ... Approximate to our current pre-industrial levels. Based on CO2, temperatures and

Message 10 of 20
, Mar 12 1:49 PM

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>
> 1) the time frame of interest is in years BP to years BP

115,000BP to 110,000BP -- I have stated this on several occasions.

> 2) what you think the total radiative forcing is for that period and how
> you arrived at this number

Approximate to our current pre-industrial levels. Based on CO2, temperatures and ice cover regimes.

> 3) what you think the change in global average temperature is and how you
> arrive at this number

The change in global average temperature is estimated (at the low end) by the Dome C core and is 2'C of additional warming as the arctic melts due to albedo change. Current models hold surface air temperatures rising by 5-11K as soon as the ice melts and our models hold a much higher surface air temperature rise once the arctic reaches a perpetual ice-free state. So an additional 2C of warming is a low-end estimate for increasing temperature once the arctic melts.

In addition, as compared to the Eemian, we currently have 105ppmv more Co2 and 850 ppbv more CH4.

By any estimation, except the discredited and felonious obfuscations of the industry-sponsored charlatan few, the global temperatures will rise an additional 3-7K by 2100. I expect it to be much, much worse if we do not immediately work toward mitigation.

>
> *We can discuss this.
>

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